The present invention relates to security documents such as banknotes or the like including security devices for visually verifying the authenticity of the security document, and is particularly concerned with the use of a light source which interact with the security device to enable such visual verification.
A wide variety of security devices for security documents, such as banknotes, traveller""s cheques, or the like, have been previously proposed. Such security devices are provided in order to make falsification and counterfeiting of the security documents difficult. Amongst those considered to be effective for use in banknotes and like security documents are security devices which modify the characteristics of an impinging light beam. Such modification is generally detected by a photo-sensitive device which detects the light beam reflected from the security document and, by analyzing the characteristics of the reflected beam, verifies the authenticity of the security document. According to one known security document verification system, a diffractive device is applied to the surface of a banknote. The output of a laser diode is passed through a lens system to produce a beam of light which is deflected onto the diffractive device on the surface of the banknote. The diffractive device reflects the incident beam to thus generate a diffracted beam. One or more images are produced by projecting the diffracted beam onto a viewing screen. The characteristics of the diffractive device are chosen so that a preselected image is reflected onto the viewing screen, thus enabling the visual verification of the authenticity of the security document.
Such methods of verification, however, require the use of a complex system of dedicated laser beam sources, mirrors, lenses and projected image viewing screens. Accordingly, verification of the authenticity of security documents bearing such security devices is only possible by persons possessing the necessary verification equipment, and cannot be conveniently carried out by many retail outlet staff and like persons who wish to verify the authenticity of banknotes, cheques, traveller""s cheques and such documents.
The aim of the invention is to provide a method of verifying the authenticity of a security document, which method is simple and convenient to use for a large number of persons who would wish to do so.
A further object of the invention is to provide a method of verifying the authenticity of a security document which does not require complex, dedicated verification equipment.
Another object of the invention is to provide a method of verifying the authenticity of a security document which ameliorates or overcomes problems of known o authenticity of security documents.
With thin m mind, one aspect of the present invention provides a method of verifying the authenticity of a security document, the security document including a first at least partially transparent portion and an optical projection element within or superposed with the first at least partially transparent portion, the optical projection element acting to transform a light beam passing from a light beam source through said first at least partially transparent portion into a patterned beam of selected design, the method including the steps of:
positioning the security document such that the light beam is transmitted through the first at least partially transparent portion and the patterned beam is projected onto a viewing surface, and
verifying the presence of a patterned image by the impingement of the patterned beam on the viewing surface.
Preferably, the security document also includes an opacifying portion, the method further including the step of:
folding the security document such that the patterned beam is caused to impinge upon the opacifying portion which thus acts as the viewing surface.
Preferably, the opacifying portion of the security document is remote from the first at least partially transparent portion.
Preferably, the light beam source is a directional light beam source. In one embodiment, the light beam source is a point-of-sale light source device, such as a laser or an LED based device.
Conveniently, the light beam source may be a bar code scanner.
In one embodiment, the optical projection element acts to generate the patterned beam by diffraction of the light beam transmitted through the security document.
Advantageously, the security document may include a second at least partially transparent portion, the method further including the step of:
folding the security document such that part only of the light beam from the light beam source passes firstly through the second at least partially transparent portion before being transmitted through said first at least partially transparent portion, said second at least partially transparent portion thus acting as a pseudo point light source.
In one embodiment of the invention, the security document includes an optical image or device, applied to the opacifying portion, which interacts with the patterned beam impinging on the opacifying portion to create a visual security effect, the method further including the step of:
verifying the presence of the visual security effect.
The optical image or device may be, for example, a printed image substantially corresponding to or complementing the patterned image projected onto the viewing surface. In addition, the optical image or device may be a reflective foil OVD or other like device.
Another aspect of the invention provides a security document including a first at least partially transparent portion and an optical projection element within or superposed with the first at least partially transparent portion, the optical projection element acting to transform a light beam passing from a light beam source through the first at least partially transparent portion into a patterned beam of selected design.
Preferably, the security document further includes an opacifying portion for impingement of the patterned beam thereupon.
The opacifying portion and the first at least partially transparent portion are preferably remote from each other.
In one embodiment, the optical projection element acts to generate the patterned beam by diffraction of the light beam passing through the security document.
In a preferred embodiment of the invention, the security document includes an at least partially transparent substrate having first and second opposing faces, and an opacifying layer applied to at least one of the faces, the first at least partially transparent portion beam applied to leave an uncoated area on the at least one surface.
The security document may include a second at least partially transparent portion for transmitting part only of the light beam from the light beam source, the second at least partially transparent portion thus acting as a pseudo point light source.
In one embodiment of the invention, the security document includes an optical image or device, applied to the opacifying portion, which interacts with the patterned beam impinging on the opacifying portion to create a visual security effect.
A further aspect of the present invention provides a method of producing a security document as described above, including the steps of:
forming an at least partially transparent substrate having first and second opposing surfaces, coating at least one face of the substrate within an opacifying layer, the opacifying layer being applied to leave a first uncoated area on the at least one surface,
conveying the optical projection element into position over the first uncoated area, and
transferring the optical projection element onto the substrate.
In one variant, the optical projection element is conveyed into position over the first uncoated area by and on a transfer foil.
Preferably the optical projection element is transferred from the foil onto the substrate by hot stamping.
It is preferably that at least one optically variable device is also conveyed into position over the first uncoated area and transferred onto the substrate together with the optical projection element.
According to another variant, the optical projection element may be transferred onto or into the substrate by embossing.
In one embodiment of the method of producing a security document, the opacifying layer is applied to also leave a second uncoated area on the at least one surface, the second uncoated area acting as a pseudo point light source when a light beam passes through the security document in the second uncoated area.
The method of producing a security document may also include the step of:
applying an optical image or device to an opacifying portion of said opacifying layer.
The optical image or device may be applied to the opacifying portion by printing.
The optical image or device may alternatively be a reflective foil OVD or like device and may be applied to the opacifying layer in the same manner as the optical projection element.
Yet another aspect of the present invention provides a method of verifying the authenticity of a security document, the security document including a first at least partially transparent portion, and an optical projection element within or superposed with the first at least partially transparent portion, the optical projection element acting to transform a light beam passing from a light beam source through said first at least partially transparent portion into a patterned beam of selected design, the method involving the steps of:
positioning the security document so as to enable a user to look at the light beam source through the first at least partially transparent portion, and verifying the presence of an image corresponding to the patterned beam in the user""s field of vision.
Conveniently, the light beam source may produce substantially collumated light, and this collumated light may be white light.
Preferably, the light beam source is located at a sufficiently remote distance from the security document that the light beam passing through the optical projection element is substantially collumated light.
In one embodiment of the invention, the light beam source produces substantially non-collumated light, the method including the step of:
placing a screen having a window between the light beam source and the optical projection element, such that the light beam from the light beam source passing through the window is substantially collumated light.
The screen may be constituted by an opacifying portion of the security document.
The window may be constituted by a second at least partially transparent portion of the security document.
Preferably, the first and second at least partially transparent portions are remote from each other in order to enable the window to be conveniently placed between the light beam source and the optical projection element.
A further aspect of the invention provides a security document including a first at least partially transparent portion, an optical projection element within or superposed with the first at least partially transparent portion, the optical projection element acting to transform a light beam passing from a light beam source through said first at least partially transparent portion into a patterned beam of selected design, and a second at least partially transparent portion located remotely from the first at least partially transparent portion, the security document being foldable such that the second at least partially transparent portion is able to be placed between the light beam source and the optical projection element in order that the light beam from the light beam source passing through the second at least partially transparent portion is substantially collumated light.